This invention relates generally to an all mechanical acceleration detection instrument, and more particularly, one which is adapted to detect the existence of a "zero" G condition over a predetermined time interval.
With the advent of the space age, weightlessness or "zero" G is a condition which is experienced by orbiting satellites, missiles and other vehicles projected out beyond the Earth's gravitational pull.
Under varying circumstances, depending on the application, it becomes important to be able to detect this "zero" G condition. For example, where intercontinental ballistic missiles are concerned, where these vehicles are carrying nuclear war heads with their potential for devastating destruction, it is important that some fool proof scheme be implemented which precludes these missiles from being placed in an armed condition or, even detonating prematurely.
In such an application, obviously, it is only desirable to have the missile armed when it is in its ballistic or unpowered portion of flight before reentry. Prior to that, the vehicle or missile must be maintained in a "safe" condition so as to avoid the obviously devastating effects of a fall back to earth or detonation on the ground while the missile is transported.
If the trajectory of a missile is analyzed, it is seen to include three basic segments. The initial liftoff phase, the ballistic or unpowered mode during which time the missile is arching through space and being redirected upon reentry towards its target, and the reentry phase of the flight. Typically, the ballistic or unpowered mode which includes the weightless or "zero" G portion of the flight, will extend for a relatively, significant portion of time. Typically, such a condition might exist for 10 minutes. Recognition of this fact enables the development of a safing-arming scheme which precludes the premature firing of the war head on the missile. This is due to the fact that a "zero" G condition cannot be simulated on Earth for such a period of time. Therefore, if an apparatus could be developed which was responsive to the existence of a "zero" G condition for this period of time, and the firing sequence of the missile included the operation of this apparatus as a portion thereof, the premature firing could be avoided.
Of course, the importance of such an apparatus to the proper functioning of other space satellites or vehicles is apparent.
For other reasons, there is no satisfactory method of performing this function. Deficiencies of presently available systems include large size, over complication, radiation susceptibility, large electrical power requirements, and poor reliability.
It is therefore a primary object of this invention to provide an apparatus which is capable of monitoring a "zero" G condition for a specified period of time and yet which is relatively small, simple, and substantially all mechanical so as to require minimal electrical power and to be insensitive to the effects of radiation.